Very Weird Xbox Problem

I dont know quite whats happening.. i tried removing Mods that would suck up Power... but to no Avail.Heres whats going on.Im trying to play Halo 2 over Xbox live. and i have a dual boot environment so im able too. now when i laod the game up.. bout 5-10 mins into the game. even less sometimes the Light around the Eject button seems to Dim out. it flickers while loggin into Xbox live. when it does go extremely dim, The xobx either Freezes. OR. just shuts off entirely. any clues on what the hell is going on? im not really a newb i know what im doing. but this is just stumping the hell out of me.

boy i sure hope not. if it helps ANY at all. it seems to run fine in Modded mode. though i havent done anything for an extended amount of time on it, not in a long while. mayb ill do some Trial and error tests